1. Field of the Invention
This invention relates to a process for refining and separating all petroleums and/or related materials, including natural materials (such as, petroleum gas, crude oils, bitumens, oils from oil-sands or oil-shales, tars from tar-sands, etc.), petroleum fraction or fractions derived from said natural materials, and refinery streams and products and, more particularly as concerned with a novel method for removing and separating asphaltic constituents and/or nonhydrocarbon constituents by contacting said petroleums and/or said related materials with added asphaltenes, precipitating said constituents together with said added asphaltenes, and recovering an oil (and/or gas) having a reduced concentration of said constituents. In various processes according to the method provided by the present invention, asphalt or asphaltenes can also be recovered.
2. Description of Prior Art
Feedstocks for cracking processes are now usually the residue or heavy distillate from a distillation sequence. However, as the occasion demands, whole crudes may also serve as the cracking feedstocks and, when this is the case, the crude must be desalted prior to the cracking process. Like still residue, heavy crude petroleums usually contain substantial amounts of asphaltic constituents, which are not only regarded as the coke-forming constituents in many thermal processes but also the source of carbon depositing on the catalyst for cracking process, thus limiting the service life of the catalyst and the capacity of the catalytic cracking unit. Crude oils contain appreciable amounts of organic nonhydrocarbon constituents, mainly sulfur-, nitrogen-, and oxygen-containing compounds, in smaller amounts, organometalic compounds in solution and inorganic salts in colloidal suspension with asphaltenes and resins. These constituents appear throughout the entire boiling range of the crude oil but do tend to concentrate mainly in the nonvolatile fractions, especially asphaltenes and resins. In minute amounts, these compounds can cause serious corrosion problems, catalyst deactivation, degrading of product quality, health hazard, etc.
In general, there is an approximate correlation between the content of the nonhydrocarbon constituents and the content of the asphaltic constituents of a petroleum stock--the higher the asphaltic constituents content, the higher the nonhydrocarbon constituents content. It is, therefore, often deemed necessary that the asphaltic constituents be removed from feedstocks for cracking and other refining processes.
There are a number of methods which are directed at upgrading feedstocks and separating petroleums and related materials by removal of the asphaltic constituents and the nonhydrocarbon constituents. These conventional methods and processes may be summarized as follows:
1. Flash distillation PA1 2. Vacuum flashing PA1 3. Viscosity breaking PA1 4. Coking PA1 5. Solvent treatment PA1 6. Caustic treatment PA1 7. Gas treatment PA1 8. Oxidative treatment PA1 9. Adsorbent treatment 10. Acid treatment PA1 11. Precipitation with reactive metal salts, etc.
The solvent treatment method is most effective in removing the asphaltic constituents, however it has been subject to considerable economic and operational disadvantages as all other conventional methods have, which often require special equipment and/or severe operating conditions. Most of these conventional methods are not applicable to the treatment of crude petroleums because of the large volumes and the high treatment costs. Some of these methods produce wastes which require special handling, and pose serious disposal problems.